Mosher et al, J. Org. Chem., 1958, 23, 1257-1261 describe the synthesis of DL-5-(β-chlorosulfonylethyl)hydantoin and L-5-(chlorosulfonylmethyl)hydantoin by the chlorination in aqueous media of DL-homocystine hydantoin and L-cystine hydantoin respectively.
WO 02/074767, WO 2004/024698 and WO 2006/065215 disclose classes of hydantoin-containing metalloproteinase inhibitors that are useful in therapy. Key intermediates useful in the synthesis of certain of the compounds disclosed in WO 02/074767, WO 2004/024698 and WO 2006/065215 are sulfonyl chlorides of general formula:

Specific sulfonyl chlorides that are disclosed in WO 02/074767 and/or WO 2004/024698 and/or WO 2006/065215 are:    (RS)-2-(2,5-dioxo-4-imidazolidinyl)-1-ethanesulfonyl chloride;    (R)-(2,5-dioxo-4-imidazolidinyl)methanesulfonyl chloride;    (S)-(2,5-dioxo-4-imidazolidinyl)methanesulfonyl chloride;    (RS)-(4-methyl-2,5-dioxo-4-imidazolidinyl)methanesulfonyl chloride;    (RS)-(4-ethyl-2,5-dioxo-4-imidazolidinyl)methanesulfonyl chloride;    (RS)-(4-methyl-2,5-dioxo-4-imidazolidinyl)ethanesulfonyl chloride;    (RS)-(4-ethyl-2,5-dioxo-4-imidazolidinyl)ethanesulfonyl chloride;    (4S)-(4-methyl-2,5-dioxo-4-imidazolidinyl)methanesulfonyl chloride;    (4R)-(4-methyl-2,5-dioxo-4-imidazolidinyl)methanesulfonyl chloride;    (4S)-(4-ethyl-2,5-dioxo-4-imidazolidinyl)methanesulfonyl chloride; and    (4S)-(4-cyclopropyl-2,5-dioxoimidazolidin-4-yl)methanesulfonyl chloride.
The sulfonyl chlorides specifically disclosed in WO 02/074767, WO 2004/024698 and WO 2006/065215 were prepared either by:                (i) chlorination in aqueous media of the corresponding disulfide derivative essentially as described by Mosher; or        (ii) by analogous chlorination in aqueous media of the corresponding benzylsulphide derivative.        
We now disclose an alternative and improved process for the synthesis of hydantoin-containing sulfonyl chlorides of the above type.